1. Field
The present application is directed to the family of resettable circuit interrupting devices and systems which include, without limitation, ground fault circuit interrupters (GFCI""s), arc fault circuit interrupters (AFCI""s), immersion detection circuit interrupters (IDCI""s), appliance leakage circuit interrupters (ALCI""s), circuit breakers, contactors, latching relays and solenoid mechanisms. More particularly, the present application is directed to a reset system in such devices and systems which is capable of being xe2x80x9clocked outxe2x80x9d such that it cannot be reset by a user if a portion of a circuit interrupting mechanism becomes non-operational or if an open neutral condition exists.
2. Description of the Related Art
The electrical wiring device industry has witnessed an increasing call for circuit breaking devices or systems which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with ground fault circuit interrupters, for example. Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894, use a trip mechanism to mechanically break an electrical connection between one or more input and output conductors. Such devices are resettable after they are tripped by, for example, the detection of a ground fault. In the device discussed in the ""894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the connection between input and output conductors) includes a solenoid (or trip coil). A test button is used to test the trip mechanism and circuitry used to sense faults and a reset button is used to reset the electrical connection between input and output conductors.
However, instances may arise where an abnormal condition, caused by for example a lightening strike, occurs which may result not only in a surge of electricity at the device and a tripping of the device but also a disabling of the trip mechanism used to cause the mechanical breaking of the circuit. This may occur without the knowledge of the user. Under such circumstances an unknowing user, faced with a GFCI which has tripped, may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to be reset without the ground fault protection available.
Further, an open neutral condition, which is defined in. Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (verses load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, current GFCI devices which have tripped, may be reset even though the open neutral condition may remain.
The present application relates to resettable circuit interrupting devices, such as but not limited to GFCI devices, that include a reset lock-out mechanism which prevents the resetting of electrical connections (or continuity) between input and output conductors if the circuit interrupter used to break the connection is non-operational or if an open neutral condition exists.
The circuit interrupter includes a trip mechanism used to cause the mechanical or electrical breaking of continuity between the input and output conductive paths or conductors and the sensing circuitry used to sense faults.
In one embodiment, the circuit interrupting device includes a housing, an input conductive path and an output conductive path. Preferably, the input conductive path is disposed at least partially within the housing and is capable of being electrically connected to a source of electricity. Preferably, the output conductive path is also disposed at least partially within the housing and is capable of conducting electrical current to a load when electrical continuity is established with the input conductive path. Electrical continuity between the conductive paths may be established using electromechanical mechanisms, such as movable electrical contacts and solenoids, or using semiconductor type switching devices. The device also includes a circuit interrupter disposed within the housing and configured to break electrical continuity between the input and output conductive paths in response to the occurrence of a predetermined condition. Predefined conditions include, without limitation, ground faults, arc faults, appliance leakage faults, immersion faults and a test cycle.
In response to the occurrence of the predefined condition, a reset lock-out operable in a lock-out position or state and in a reset position or state is set to one of the states. In the lock-out position or state, the reset lock-out inhibits resetting of electrical continuity between the input and output conductive paths, and in the reset position or state, the reset lock-out does not inhibit resetting of electrical continuity between the input and output conductive paths. The circuit interrupting device also includes a reset mechanism operatively associated with the reset lock-out and the circuit interrupter. Activation of the reset mechanism activates the circuit interrupter which facilitates changing the operable position or state of the reset lock-out from the lock-out position or state to the reset position or state.
In another embodiment, the circuit interrupting device includes a housing, an input conductor disposed at least partially within the housing and capable of being electrically connected to a source of electricity, and an output conductor disposed at least partially within the housing and capable of conducting electrical current to a load when electrically connected to the input conductor. In this embodiment, electrical connections between the conductors may be established using electromechanical mechanisms or semiconductor type switching devices.
The device also includes a circuit interrupter that is disposed within the housing and configured to break the electrical connection between the input and output conductors in response to the occurrence of a predetermined condition. Again, predefined conditions include, without limitation, ground faults, arc faults, appliance leakage faults, immersion faults and a test cycle. In response to the occurrence of the predefined condition, a reset lock-out operable between a lock-out position (or state) and a reset position (or state) is set to one of the positions. In the lock-out position, the reset lock-out inhibits resetting of the electrical connection between the input and output conductors, and in the reset position, the reset lock-out does not inhibit resetting of the electrical connection between the input and output conductors. The circuit interrupting device also includes a reset mechanism operatively associated with the reset lock-out and the circuit interrupter. Activation of the reset mechanism activates the circuit interrupter which facilitates changing the operable position of the reset lock-out from the lock-out position to the reset position.
The circuit interrupter includes a trip mechanism and fault sensing circuitry. The trip mechanism may be an electromechanical mechanism (e.g., a solenoid or relay), a solid state mechanism or other mechanisms that may be used to break electrical continuity. A preferred electromechanical trip mechanism includes a coil assembly, a movable plunger and a banger. The movable plunger is responsive to energizing of the coil assembly, and the banger, which is attached to the plunger, moves when the plunger moves. Movement of the banger permits the reset lock-out to change operable positions.
Preferably, the reset mechanism includes a reset button that is coupled to the reset lock-out, and reset contacts that are activated when the reset button is depressed. When the reset button is depressed, the reset contacts close a circuit that, in the embodiment shown, activates the test cycle causing the circuit interrupter to activate permitting the reset lock-out to change operable positions.
This arrangement prevents the circuit interrupting device from being reset if the circuit interrupter is inoperative, since the circuit interrupter has to be activated in order to reset electrical continuity between the input and output conductive paths or conductors. In other words, this arrangement ensures that once the circuit interrupting device has been reset, it has the ability to again break electrical continuity between the input and output conductive paths because the sensing circuitry and trip mechanism of the circuit interrupter are utilized for resetting the continuity.
This arrangement also ensures that when such circuit interrupting devices are initially installed and energized the proper electrical connections have been made. For example, if the circuit interrupting device is a GFCI receptacle, improper electrical connections between input and output conductors on the receptacle and the line (hot) and load wires in a household junction box may cause a fault that is sensed by the circuit interrupter causing its trip mechanism to activate.
In addition, in the embodiments where the trip mechanism of the circuit interrupter uses power supplied to the device in order to activate, the arrangement of tying the resetting of the device with the operation of the circuit interrupter also prevents the circuit interrupting device from being reset if an open neutral condition exists with the wiring supplying electrical power to the device, since the circuit interrupter has to be activated in order to reset electrical continuity between the input and output conductive paths or conductors.
The present application also relates to a method for interrupting and resetting electrical connections in fault interrupting devices, such as the device above. The method involves sensing the occurrence of a predefined condition and breaking electrical continuity between input and output conductive paths or conductors when the predetermined condition is sensed. Preferably, a circuit interrupter having the above-described coil assembly, plunger and banger, is used to break continuity between the conductive paths.
After electrical continuity between the input and output conductive paths is broken, a lock-out mechanism is enabled so as to inhibit reestablishing electrical continuity between the input and output conductive paths. To reset the device, a reset mechanism is activated causing the circuit interrupter to operate and thus disable the lock-out mechanism and electrical continuity between the input and output conductive paths to be reestablished.